涡轮叶片气膜冷却孔高速电火花加工防背伤方法

Back-strikes happened in the film cooling holes high speed EDM drilling is a bottle neck for the rapid developments of aircraft engine and gas turbine manufacturing in China. Aiming at solving the problem of sudden aggregation of discharge conditions while a tilt film cooling hole being broken through, which results in the instability of machining, this study will focus on the following contents. (1) Direct observation and analysis of special physical phenomena while a tilt film cooling hole being broken out by using a unique design of experimental setup; (2) Modeling and simulation of the specific flow field in the discharge gap while a tilt hole being broken out; (3) Proactive measures for improving the flow field and discharge conditions which lead to a better machining stability; (4) Development of reliable and fast break out detection method based on the machine learning technique; (5) Implementation of precise and effective control strategies for preventing the blades from back-strike; (6) Verification for the effectiveness of the above mentioned researches by conducting the test cut machining. During the study, two scientific issues will be addressed and solved: (1) What really happens in the discharge gap during the tilt film cooling hole being broken out by high speed EDM drilling? (2) How to resolve the space domain problem i.e. break out event by utilizing retrievable information from time and frequency domain in a real-time manner? The achievement of this study may dramatically leverage the turbine blades manufacturing technology in China.

涡轮叶片气膜冷却孔高速电火花加工中的背伤问题是制约我国航空发动机和燃气轮机制造发展的一个瓶颈。针对气膜冷却斜孔穿透瞬间放电条件突然恶化所引起的加工不稳定及控制困难等问题，本项目将重点研究：（1）采用独特的实验设计和实验方法直接观测斜孔穿透瞬间放电间隙物理现象并进行分析；（2）针对穿透过程特殊流场条件进行分析和仿真；（3）提出并采取主动改善斜孔穿透过程间隙流场及放电条件的方法和措施以提高加工过程的稳定性；（4）提出并实现基于机器学习的斜孔穿透精准检测方法；（5）提出并实现避免背伤的斜孔穿透过程可靠控制策略；（6）采用模拟加工实验方式验证上述方法的有效性。本项目试图解决两个科学问题：（1）斜孔高速电火花加工穿透瞬间及穿透过程中的极间物理现象的获取与认知；（2）如何有效利用可获取的“时域与频域信息”在线实时求解“空域事件”即“斜孔穿透”问题。本项目的研究成功有利于大幅度提升我国涡轮叶片制造水平。

涡轮叶片气膜冷却孔高速电火花加工中的背伤问题是制约我国航空发动机和燃气轮机制造发展的一个瓶颈。针对气膜冷却斜孔穿透瞬间放电条件突然恶化所引起的加工不稳定及控制困难等问题，本项目将重点研究以下内容：（1）设计直接观测实验方法直接观测斜孔穿透瞬间放电间隙物理现象并运用多物理场仿真的方法仿真穿透过程，揭示放电机理；（2）通过改善斜孔穿透过程间隙流场及放电条件的方法和措施以提高加工过程的稳定性；（3）提出基于机器学习中状态图的方法实现斜孔穿透精准检测方法；（4）实现避免背伤的斜孔穿透过程可靠控制策略。最终综合试验验证上述方法的有效性和可行性。最终解决了斜孔高速电火花加工穿透瞬间及穿透过程中的极间物理现象的获取与认知，以及利用放电过程中“时域与频域信息”解决了斜孔穿透检测和控制问题。